The present invention relates to a method of estimating magnetic flux in an electromagnetic actuator for controlling an engine valve.
As is known, tests are currently being conducted of internal combustion engines of the type described in Italian Patent Application BO99A000443 filed on Aug. 4, 1999, wherein the intake and exhaust valves are operated by electromagnetic actuators. Electromagnetic actuators definitely have various advantages, by enabling optimum control of each valve in any operating condition of the engine, unlike conventional mechanical actuators (typically, camshafts) which call for defining a valve lift profile representing no more than an acceptable compromise for all possible operating conditions of the engine.
An electromagnetic valve actuator for an internal combustion engine of the type described above normally comprises at least one electromagnet for moving an actuator body of ferromagnetic material and connected mechanically to the respective valve stem; and, to apply a particular law of motion to the valve, a control unit drives the electromagnet with time-variable current to move the actuator body accordingly.
However, for the electromagnet to be driven so as to move the actuator body according to the desired law of motion, various characteristic quantities of the systemxe2x80x94in particular, the magnetic flux acting on the actuator bodyxe2x80x94must be estimated in substantially real time.
It is an object of the present invention to provide a method of estimating magnetic flux in an electromagnetic actuator for controlling an engine valve, and which is both cheap and easy to implement.
According to the present invention, there is provided a method of estimating magnetic flux in an electromagnetic actuator for controlling an engine valve, as claimed in claim 1.
The present invention also relates to a device for estimating magnetic flux in an electromagnetic actuator for controlling an engine valve.
According to the present invention, there is provided a device for estimating magnetic flux in an electromagnetic actuator for controlling an engine valve, as claimed in claim 6.